Attachment D - Stormwater and Water Quality report

garden/accessible soil); 109mg/kg of copper; and 1220 mg/kg of zinc. All impacted
material occurs at shallow depth (0-200mm) in fill material present across the lot, and
attenuates rapidly with depth, with all the (200-500mm) samples collected from natural
insitu soils at these locations reporting metal concentrations below the EILs.

Lot 1 RP87371:

Metal concentrations in excess of Qld EPA EILs remain onsite (as shown on Figure 3),
with maximum concentrations being: 112mg/kg of arsenic (also above HIL “A”
guidelines); 143mg/kg of copper; 148mg/kg of chromium (III); and 884 mg/kg zinc.
Although there is no nominated guideline for boron, two samples collected from this
allotment also reported concentrations of boron in excess of the acknowledged
background concentrations (maximum concentration detected was 723mg/kg). All
impact occurs in samples collected at shallow depth (0-200mm) in fill material present
across the lot, however in some locations the impact has not been vertically delineated.

Lot 5 SP173771:

In the area to the east and south east of the former boiler building (as shown on Figure
4) metal concentrations in excess of Qld EPA commercial/industrial health based
investigation levels (HIL “F”) guidelines remain onsite, with maximum concentrations
detected being: 8820mg/kg of arsenic; 8930mg/kg of copper; and 30400mg/kg of
chromium. This impact occurs at shallow depth (0-200mm) in fill material present in
this area of the lot, however in one location it has not been vertically delineated.

Although no nominated guideline exists for boron, these samples also reported
concentrations of boron in excess of the acknowledged background concentrations
(maximum concentration detected was 9410mg/kg).

In other areas of Lot 5, metal concentrations in excess of Qld EPA EILs remain onsite,
with maximum concentrations detected in other areas of the site being: 60mg/kg for
arsenic, and 131mg/kg for chromium(III). All impacted material occurs at shallow
depth (0-200mm) in fill material, however in some areas the impact has not been
vertically delineated.

Lot 7 SP173771
Areas of residual soil impact across this lot are shown in Figure 5.

Residual soil impact in locations F2 and F3 exceeds Qld EPA EILs for arsenic, copper
and chromium (IIT). As part of soil remediation works undertaken at the site in the year
2000, this area was capped by a 500mm clay layer. This clay capping layer has a
confirmed density ratio of 95.5%. This capping layer was covered by 100mm of clean
soil.

Residual soil impact in the location of the former evaporation pond exceeds Qld EPA
HIL”F” levels for arsenic, and the EILs for copper and chromium (III). As part of soil
remediation works undertaken at the site in 2000, this area was backfilled with soil
excavated during the replacement of the causeway at the site, the soil excavated from
behind the boiler as part of other soil remediation works onsite, and imported clay fill.
This backfill was then capped by a 500mm clay layer. Sections of this clay capping